Erosion and Sediment Pollution Control Program Manual.pdf

stabilization; cutting of existing cut slopes; inlet and endwall cleaning; reshaping and cleaning
drainage ditches and swales; pipe cleaning; pipe replacement; support activities incidental to
resurfacing activities such as minor vertical adjustment to meet grade of resurfaced area; ballast
cleaning; laying additional ballast; replacing ballast, ties and rails; and other similar activities.
The existing road cross-section consists of the original graded area between the existing toes of
fill slopes and tops of cut slopes on either side of the road and any associated drainage
features.
Roadbed -----That portion of a roadway extending from curb line to curb line or from shoulder line to
shoulder line. Divided highways are considered to have two roadbeds.
Rock Chimney Drain -----A comparatively small vertical extension of a rock toe bench maintained
within a constructed earthen fill to facilitate drainage of surface runoff from the top of the fill into
the rock toe bench. The purpose of this drainage is to prevent concentrated flows and the
formation of erosion gullies on the outslope(s) of the fill and to remove some of the sediment
load prior to discharge to receiving surface waters.
Rock Construction Entrance -----A method of stabilizing a temporary construction entrance to a
project site from a paved roadway by placement of AASHTO #1 stone. See Standard
Construction Detail #3-1.
Rock Filter -----A sediment barrier constructed from riprap and filter stone. See Standard Construction
Detail # 4-14.
Rock Filter Berm -----A sediment barrier constructed across a right-of-way or below a disturbed area.
Due to the cost of construction, this BMP should be used only where no other BMP is feasible.
Rock Filter Outlet -----A sediment barrier constructed at points where concentrated flow is anticipated
at a silt fence or straw bale barrier or where concentrated flow has caused the failure of a
barrier.
Rock Toe Bench -----An excavated and rock-filled structure constructed at the base of a fill where the
foundation is located in water or in saturated or unstable soils to ensure proper drainage and
support for the overlying earthen fill.
Rock Vanes -----Rock structures used in FGM-based restoration projects; slope and shape of the rock
vane reduces the velocity of the water as it flows up the vane and accelerates the flow as it rolls
water away from the bank towards the center of the stream; the net effect is to protect the bank
from erosion and to direct the force of the water into the center of the stream for sediment
transport.
ROD -----Record of decision.
Rodent Gate -----An appurtenance at the outlet end of a drainage pipe that swings outwards to permit
flow and detritus to pass, yet prevents rodents and other animals from entering and potentially
blocking the system.
Rolled Erosion Control Products (RECPs) -----Temporary, degradable or long-term, non-degradable
material manufactured or fabricated into rolls and designed to be rolled out and staked onto an
exposed surface to reduce soil erosion and promote the growth of protective vegetation.
Root Zone -----That part of a soil which can be penetrated by plant roots.
Rooted -----Expression indicating that a bank has been excavated and the end of a structure, such as a
check dam, dike, etc., has been placed in the cavity, thus retarding future streamflow around the
end of the structure — flanking.
Rootwad -----A tree stump with roots that are strategically placed in a stream bank as part of rebuilding
or restoring the bank; it is typically used to control erosion on outside bends; rootwads are
angled upstream with the root mass facing the flow; this serves to dissipate energy by receiving
the brunt of the stream energy.
Roughness -----The resistance of streambed materials, vegetation, or liners to the flow of water in a
channel or swale.
Roughness Coefficient -----A dimensionless value in Manning’s Equation that varies depending upon
the type of lining and flow depth.
Routing -----The process of transposing an inflow hydrograph through a structure and determining the
outflow hydrograph from the structure.
Rubble -----Rough, irregular fragments of broken rock or concrete.
Runoff -----That portion of a rainfall or snowmelt that flows over the surface.
363-2134-008 / March 31, 2012 / Page 543